A seaside slayer suspect called one of the victims’ families from her cell phone, police said.

After Melissa Barthelemy disappeared in July 2009, a man made calls from her cell phone on three days that month, telling her teenage sister that Barthelemy was a “whore,” a police source told Newsday.

NYPD officers keeping track of the phone’s signals traced it to midtown Manhattan, near Penn
Station, the source said, but the suspect hung up before police could pinpoint an exact location.

The Suffolk County Police Department declined to comment on the calls, saying only that the investigation is ongoing.

Those 2009 phone calls are now part of a serial killer investigation — Barthelemy’s remains were one of four bodies found on Gilgo Beach on Long Island.

The police source also said someone tried to access Barthelemy’s voice mail from Massapequa. Cops are scoping out two hotels in the area, the Rodeway Inn and the Best Western, for surveillance video, the source said.

Police suspect they’re chasing a serial killer who hunted victims selling sex on Craigslist.